Low thermal conductivity attachment



United States Patent Ofitice 3,355,051 Patented Nov. 28, 1967 8 Claims. (31. 220-15 This invention relates to low thermal conductivity attachments, such as supports, sustainers, eenterings or the like, for transmitting forces.

The design of equipments meant to operate at a temperature considerably different from ambient, and in particular at low or very low temperatures, like that of liquid nitrogen, helium or hydrogen will necessitate the use of vessels the thermal insulation of which should be made with particular care. Among such equipments, for instance, are electric coils for creating intense electric fields and which, for this reason, must be brought either to low temperatures in order to take advantage of the improvement of the conductivity, or the very low temperatures, in the case of superconductive coils. In such cases one may use a double-walled chamber, the interspace between the two walls being under vacuum, if necessary with an intermediate powder material or an anti-infrared shield.

The inner wall forms a vessel containing the equipment which must operate at low temperature. The cooling of this vessel is ensured either by suitable heat-exchangers or by providing a liquefied gas such as hydrogen or helium, for instance. Liquid helium, for example, is rather lightweight so that, it put in the vessel, no special features are required for the supporting of the latter. The vacuum concentric vessels are held one to the other by the neck of the container, which allows the filling with liquified gas and as long as no heavy equipment is present in the vessel, the supporting at filling neck level is adequate for holding the inner vessel.

However, this arrangement is no longer adequate it the Vessel must contain equipment which are heavy or which apply forces. It is then necessary to provide for supports or sustainers located, for instance, in the lower part of the vessel, in order to transmit the Weight of the equipment, or located on the side walls so as to counteract horizontal forces.

Various solutions have already been suggested in order cross-sections for the ifilling neck and consequently large heat losses.

.Another suggestion was to hang the inner vessel from the outer vessel with straps, made of stainless steel or stratified polyester for instance. Suspension by -a network of cable for instance, in stainless steel or synthetic material has also been tried out. The drawbacks of these solutions is that they require a large bulk solid angle. Moreover, the realisation and setting raise delicate mechanical problems.

It has also been suggested that the forces from the inner vessel 'onto the outer vessel should be carried through 'le'gs made of high insulating coefficient synthetic material. However, with such arrangements, the heat losses are too high.

The present invention relates to a supporting arrangement with a high performance thermal insulation while avoiding the above-mentioned drawbacks.

The supporting arrangement according to the present invention is remarkable in particular by the fact that it comprises, for the transmission of rest or thrust forces, at least one, component working in tension.

According to another feature of this invention, the support comprises two rigid components of generally long shape, arranged parallel one to the other and overlapping on a fraction of their lengths, the ends of said rigid components making up the rest points of the support while the inner ends of said rigid elements are connected by the above-mentioned component working in tension.

The arrangement according to the invention is advantageous because the path of the heat losses is via a component working in tension. It is possible to select a very small cross-section component since its cross-section area is designed to meet strictly the force necessary for carrying in tension the load applied to it. For the sustainers which include. only components working in compression, the dimension of the elements must not only correspond to the load applied directly but it must also be adequate to resist buckling. One is then led to use much larger crosssection areas than those which would be sufiicient to carry the loads in tension and these cross-sections do not allow an adequate insulation.

According to another feature of the present invention, the above-mentioned component working in tension is made of tension resistant and heat insulating fibres, such as a synthetic fibre cable. These fibres may be advantageously made of superpolyamide, such as those with trademarks Dacron or Tergal.

This arrangement provides a good thermal insulation and is made possible by the fact that the component works in tension.

Advantageously the component Working in tension is made by an endless cable arranged as a loop and the rigid elements associated with this component comprise means for simply fastening said cable. Such an endless cable provides a safe and simple attachment.

Other features of this invention will appear in the following description, Which should not be given a limiting sense, with reference to the accompanying drawing on which:

FIGURE 1 is a vertical section, along the axis, of an arrangement according to the invention, located between two concentric Walls of an insulating multi-wall container;

FIGURE/2 is a section along line HII of FIGURE 1;

FIGURE 3 is a view comparable to that of FIGURE 1 V of another embodiment; and

FIGURE 4 is another view comparable to that of FIGURE 1 of another embodiment.

In the embodiment of FIGURE 1, the isothermal container comprises two, and possibly more, concentric parallel walls 10-11 between which is a high vacuum for insuring thermal insulation. A first support member 12, which may comprise a tube, integral with the wall 10 is provided with four slots 13, 14, 15, 16. The support member 12 may be made of stainless steel or plastics such as, for example, stratified polyester fitted, and stuck onto a metallic shoulder.

A rod 18 connected with the wall 11 is introduced into the support member 12. The rod 18 is held onto the wall 11 through a stub 19, a threaded end of the rod 18 being screwed up into said stub. This threaded connection provides a means to set the tension of the suspension and the relative positioning of the two walls 10 and 11;

A ring joint 21 enables a temporary sealing to be achieved during the setting operations; once the latter .are over, the screw 18 :and the stub 19 are tightened and the sealing is ensured, for instance, by a lip fusion argon Weld 22.

Advantageously, the rod 18 may be made of two parts, a metallic one .for the setting and sealing area, i.e. the bottom .end, and a pa 23,.made of an insulating material such as polyester, which may be fitted and/ or stuck onto the metallic part. The rod 18 and the support member 12 are connected by a flexible cable 25 placed on the tube via slots 13-15 and resting on the rod 18 via a cap 26 provided, for this purpose, with two grooves 27 and 28.

To prevent the cable 25 from running off the cap 26, a small plate 29, held for instance by a screw 30, covers the upper part of the cap 26. The cap 26 is laid on the rod 18 so that it may oscillate a little in order to accommodate the differences in tension between the different sides of the cable 25. To this end, it may comprise a shape which matches the shape of the inner end of the rod 18, for example, as a conical shaped end 32.

It is clear that, for passing from the Wall to the wall 11, the heat flow must first flow in the support member 12 and then up the sides of the cable 25 into the cap 26 and down from there to the wall 11. The thermal conductivity between the two walls is lowered because of the long heat 1 path, long with respect to the distance between walls, and moreover because of the nature of the tension working fibrous element 25. This fibrous element has a small cross-section which is made possible on one hand because of the toughness of fine fibre strands, and, on the other hand, because it obviates the problem of buckling resistance, which is not the case for a leg working in compression.

The arrangement according to the invention has a small bulk: it may be housed within a relatively small solid angle and makes easy the use of insulator with anti-infrared shield, which is not the case for strap or oblique tie-rod suspensions. Consequently, the volume where heat losses may take place is particularly small.

Finally, the setting of the arrangement is easy since the end of the rod 18 is accessible from the outside and can be moved axially in a very simple manner.

FIGURE 3 shows an embodiment in which the insulation is still improved. Between the rod 50 and the item 51 integral with the wall 52 an intermediate member or tube 53 is provided for. The rod 50 and the intermediate tube 53 are connected by a first flexible cable 55, fitted on the tube 53 as above, and on the rod 50 through a cap 56 of the same sort as the cap 26 of FIGURE 1.

The tube 53 itself is connected to the tube 51 by a second insulating cable 57 fitted also in the same manner on the tube 51 and fitted on the tube 53 through a cap 58 of the same kind as the cap 26 of FIGURE I, placed on the upper end of the tube 53. Such a support, offers an increased resistance to the flow of which has a lower heat flux, but the transversal stability, may be used together with arrangements in accordance with the embodiment of FIGURE 1.

In the embodiment of FIGURE 4, an intermediate element 63, comprising a conical part, has been provided for between the rod 61 and the outer tube 62. Such a layout might also be used for the outer tube, in the embodiment of FIGURE 1, as well as in that of FIGURE 3.

The supports according to the invention may be placed in the lower part of the vessels, in order to carry the vertical loads; they may also be placed on the side walls so as to hold the vessel against the transversal forces. They can also be provided for at the upper part, if necessary.

Naturally, the invention is by no means limited to the embodiments described and shown, which were given only by way of example.

We claim:

'1. An insulating support element for supporting and thermally isolating wall members of low temperature storage containers, said containers comprising at least an inner vessel and an outer vessel surrounding said inner vessel in spaced relation to said inner vessel in combination, comprising: 7

a first support member mounted on the surface of one of said vessels, said first support member extending toward the surface of the other vessel in the space between said vessels,

a second support member mounted directly opposite said first support member on said other vessel, said second support member extending at least partially Within said first support member, and

means including a flexible cable formed of a material of low thermal conductivity mechanically connecting the free end portion of said first support member to the free end portion of said second support member partially within said first support member with said connecting means under tension and said first support member and said second support member under compression.

2. An insulating support element according to claim 1 wherein said second support member includes a shaft having adjustment means for varying the tension on said connecting means.

3. An insulating support element according to claim 2 wherein said adjustment means is a threaded connection which serves to mount said second member on the inner surface of said outer vessel.

4. An insulating support element according to claim 3 wherein said first support member is mounted on the outer wall surface of said inner vessel, and said second support member is mounted on the inner surface of said outer vessel.

5. An insulating support element for supporting and thermally isolating wall members of low temperature storage containers, said containers comprising at least an inner vessel and an outer vessel surrounding said inner vessel in spaced relation to said inner vessel, in combination, comprising:

a first support member mounted on the surface of one of said vessels, said first support member extending toward the surface of the other vessel in the space between said vessels,

a second support member mounted directly opposite said first support member on said other vessel, said second support member extending at least partially within said first support member,

an intermediate member having an end positioned within said first support member,

connecting means for mechanically interconnecting said first support member, said second support member and said intermediate member,

said connecting means including a first flexible cable mechanically connecting said end of said intermediate member with the free end of said first support member,

a second flexible cable mechanically connecting the free end of said second support member with the other end of said intermediate member,

said second support member being partially inserted within said intermediate member, so that said first cable and said second cable are in tension and said first support member and said second support member are in compression,

said first cable and said second cable having low thermal conductivity.

6. An insulating support element according to claim 5 wherein said other end of said intermediate member extends outside said free end of said first support member.

7. An insulating support element according to claim 1 further including at least one intermediate member, said intermediate member having a first end and a second end positioned to be in nested stacked relationship with said support members, the first end of said intermediate member being mechanically connected by flexible cables to the free end of said first support member, and the second end of said intermediate member being mechanically connected by flexible cables to the free end of said second support member.

8. An insulating support element for supporting and age containers, said containers comprising at least an inner vessel and an outer vessel surrounding said inner vessel in spaced relation to said inner vessel in combination, comprising:

a first support member mounted on the surface of one of said vessels, said first support member extending toward the surface of the other vessel in the space between said vessels,

a second support member mounted directly opposite said first support member on said other vessel, said second support member extending at least partially Within said first support member,

connecting means including a flexible cable formed of a material of low thermal conductivity mechanically connecting the free end portion of said first support member to the free end portion of said second support member within said first support member with said connecting means under tension and said first support member and said second support member under compression,

said second support member includes a shaft having adjustment means for varying the tension on said connecting means,

said adjustment means comprises a threaded connection outer vessel, and said free end of said first support member includes a plurality of slots positioned around its periphery for engaging said flexible cable.

References Cited UNITED STATES PATENTS Place 220-15.56 Price 248-18 Stramaglia 248-18 Piron.

Hansen et a1. 220-15.278 Yerzley 248-358 Soldman 248-18 Lodge 248-18 Rind 220-9 James 220-15 FOREIGN PATENTS THERON E. CONDON, Primary Examiner.

for mounting said second support member on the JAMES GARRETT Examiner 

1. AN INSULATING SUPPORT ELEMENT FOR SUPPORTING AND THERMALLY ISOLATING WALL MEMBERS OF LOW TEMPERATURE STORAGE CONTAINERS, SAID CONTAINERS COMPRISING AT LEAST AN INNER VESSEL AND AN OUTER VESSEL SURROUNDING SAID INNER VESSEL IN SPACED RELATION TO SAID INNER VESSEL IN COMBINATION, COMPRISING: A FIRST SUPPORT MEMBER MOUNTED ON THE SURFACE OF ONE OF SAID VESSELS, SAID FIRST SUPPORT MEMBER EXTENDING TOWARD THE SURFACE OF THE OTHER VESSEL IN THE SPACE BETWEEN SAID VESSELS, A SECOND SUPPORT MEMBER MOUNTED DIRECTLY OPPOSITE SAID FIRST SUPPORT MEMBER ON SAID OTHER VESSEL, SAID SECOND SUPPORT MEMBER EXTENDING AT LEAST PARTIALLY WITHIN SAID FIRST SUPPORT MEMBER, AND 